Radio tube shield



g- 1936- F. HAFECOST ET AI. 2050838 RADIO TUBE SHIELD Filed April 14, 1933 Patenten! Aug. 11, 1936 UNITED STATES PATENT OFFICE RADIO TUBE SHIELD ration of Delaware Application April 14, 1933, Serial N0. 666,100

1 Claim.

'I'his invention relates to a radio tube shield, and more particularly to a form of removable shield adapted to fit the tube snugly.

The practice of shielding tubes in the more 5 modern radio sets is well understood in'the art. 'I 'he grounding of the shield on a metal chassis is sometimes efiected by a spring clip or an annular collar or receptacle.

In the present invention a method of ground- 10 ing is to run a wire 01' thin metal strip from beneath the shield to the cathode pin 015 the base or to a special pin in the base, which is grounded through a socket connection.

According to the present invention it is pro- 15 posed 130 use a metallic shield, comprising two symmetrically paired parts, said shield being shaped so as to fit closely to the bulb of the tube. By making the shield in two parts it may be quickly attached to the tube and readily removed 20 therefrom; it may also be easily conformed to the shape or contour 015 the bulb of the tube, so

! as to afiord an intimate fit therewith.

It is, therefore, an object of the present invention to provide a form of tube shield which 25 may be easily attached. to the tube, have intimate contact therewith and. be readily removed ther.efrom when desired. 'Ihe removable feature of the shield makes it adaptable for use an successive tubes upon failure of the same in opera- 30 tion.

A special object of the invention is to form the shield of thin sheet metal, having such a configuration er design that the separate or individual parts thereof may be nested for economy 35 in packing and shipping the same.

Other objects cf. the invention will manifest themselves upon a reading of the following specification.

Referring to the accompanying drawing:

Fig. 1 is a perspective view of a part which when paired with a similar part forms a shield embodying the invention;

Fig. 2 is a similar view showing one of the parts of the shield placed around. the bulb of a radio tube;

Fig. 3 is a vertical longitudinal section of a tube and the two component parts comprising the shield applied to the bulb thereof;

Fig. 4 is a horizontal section taken on the line 44 of Fig. 3;

Fig. 5 is a perspective view of a modificatio-n of the shield showing the two halves r sections spread apart;

Fig. 6 is a side view of the form shown in Fig.

and

Fig. 7 is a horizontal sectional view taken 0n the line 'I'I of Fig. 6.

Broadly the shield contemplated. by the invention comprises a removable metallic casing formed of sections or parts which wheh assem- 5 bled have an inner contour substantially conforming to the outer contour of a radio tube. The form of shield illustrated in the drawing is composed. cf tw0 symmetrical paired parts, for the sake of eonvenience designated by the reference 10 characters I and 2 when shown in an assembled. position, although it should. loe appr.eciated that these parts are duplicates of each oth-er in every respect. These parts or sections are formed from sheet metal such as ir0n aluminum, nickel or the like.

As will be noted from the drawing, the parts I and 2 are of the same general contour as the bulb 3 of present Standard radio tubes designated in the trade as type 58 and 78. Bulbs of that type are generally pear shaped, having a straight side porti0n which tapers outwardly to a maximum dian1eter slightly above the middle. The bulb then assumes the shape of a dome 4, into which is sealed a contact or terminal memher 5, said member being commonly referred to as a top cap. The lower ends of the sections I and 2 are semi-cylindrical in shape and together form a cylindrical extension which partly covers the base of the tube. Immediately adjacent this extension the parts I and 2 taper outwardly. This taper, following the general contour of the bulb, increases upwardly until the parts I and 2 reach their largest radius at a point slightly above the middle of the bulb. The parts and 2 then taper or curve inwardly so as to fit around the dome 4. In order to accommodate the top cap or terminal member 5 the upper end of the sections I am]. 2 have a circular cut away portion 6 which is of suflicient diameter to permit the protrusion of the terminal member 5 without danger of electrical contact. By this construction the shield has an inner contour which substantially coincides or conforms to the unter contour of. the radio tube and fits snugly thereagainst.

The longitudinal edges of each cf the sections I and 2 are flanged outwardly and are of Sufficient area as to form an abutting surface when the two halves or sections comprising a complete shield are positioned so as to oppose each other. Located intermediate the ends of each of the parts I and 2 is a circumferentially formed groove 1 adapted to receive a resilient spring member 8. This spring member may comprise an annulus or rin g made cf suitable spring wire and having a diameter s1ightly 1ess than the outside diameter of the shield ab the point of engagement there- With, so that when the member 8 is snapped into the groove 7 the ends of the spring wire are slightly separated, thus insuring the tension cf the member 8 being exertecl to hold the two halves or sections of the snield firmly together when assembled. It is apparent from this coustruction that the shield may be easily attachecl to a, radio tube and removed therefrom ad. will.

In the modification shown in Figs. 5 t- 7 the method of securing the 13W0 sections comprising the shield to the bulb is somewhat difierent. In this modification the groove l is eliminated and the two ha1ves a1e held permanently together by a, resilient member or spring 9, the ends of which are secured to 1ugs H) that may be attached to 01' formed integrally with each section. In this construction the shie1d. is in the nature of a bi-valve in that the t-Wo ha1ves are loosely hinged upon one of their adjacent flanged surfaces and may be sprung open sufficiently wide to permit the insertion of a. radio tube within the shield.

'Ihe invention thus far ha.s been described in connection With a radio tube having the so-called S. T. bulb, provided With the usual dome 4 and top cap 5. There arehowever various types cf radio tubes which have no top cap, as we1l as have diiferent shaped bulbs. F01 example the type 27 tube has no top cap and no dome, the bulb being known as an S. bu1b. On the other band certain tubes, as for example on the 37 type tube, have a dome but no top cap. In the event the shield is intended. for use on a tube having a. bu1b without a top cap, irrespective as 110 the type of bulb, the metal a1: the top of the sections comprising the shie1d may be continued across the top o-f ohe bulb so as to completely enclose the taube. In every instance however the contour of the parts comprising the shield comform to the shape cf the bulb whether or not it; is provided With a top cap. Certain of the modifications just described are not shown in the drawing but the construction is obvious 1:0 those skilled. in the art in view of the foregoing description.

'I'he method of connecting the shield to a 5 ground source may take any suitable form such as suggested above. F01 example such a comnection may be made by means of a spring, wire 01 the like having one end thereof electrically connected 130 the shield and the other end to a, grounded connection. As the manner or method for making this connection is a matter of couvenience it has not been illustrated.

Modifications of the invention Will suggest themselves to those skilled in the art, but it is intended to cover all such modifications as come within the scope of the appended claim.

What is claimed. is:

A conductive shield for a, radio tube of the type having a, base sealed 130 one end of the glass bulh which is provided With a dome-portion ab the other end, opposite to the base, and adapted to electrostatically screen the electrode system of said rad1'o tube from external electrical disturbances comprising a pair of nondeformable substantially similar, thin sheet metal members, each having a length substantially equal to tha.t of the tube and. having an inner contour couforming substantially t0 the outer contour of one-half of the tube, said members forming, when assemb'led With their longitudinal edges opposing each other, a casing having substantia.lly the configuration of the tube, a, projecting member formed on the outer surface cf each shield member approximately midway between its ends, said projecting members being disposed substantially diametrically opposite, and resi1ient means extending between and having its ends joined to said projecting members, said resilient means being shaped to conform to and. abutting the surface of the shield members.

FREDERICK HAFECOST. CLARENCE B. L. 'IOWNLEY. 

